Spark plug



, Z O H M K m i /I VV l W E m m w A m I mw/ www/l/wm May 15, 1928.

' INVENTOR ATTORN EYS Patented May 15, 1928.

UNITED. STATES ARTHUR R. MOSLEB,

on NEW YORK, n. Y.

i SPARK Piano.

Application filed January The object of my invention is to produce a spark plug in which novel means are employed for ensuring a gas tight joint around the center spindle, in which novel means are also employed for locking the center electrode to its spindle, and in which other novel features are incorporated, as will hereinafter appear.

A practical embodiment of my invention is represented in the accompanying drawings, in which Fig. 1 represents the spark plug in longitudinal central section.

Fig. 2 represents an end view of the sleeve of compressible material.

Fig. 3 represents a side view of the same, partly in section.

Fig. 4 represents an outer end view of the tubular wedge.

Fig. 5 represents a side view of the same partly in section.

The spark plug shell 1 has a reduced exteriorly screw-threaded inner end 2. The bore of the shell has a reduced inner end forming a restricted passage 3 and an enlarged interiorly screw-threaded outer end 4 for the reception of the bushing 8. The bore between the said inner and outer ends comprises an outwardly flaring spherical portion 5 terminating in a cylindrical portion 6, an outwardly-flaring annular shoul- .der 7 being provided at the outer end of the said cylindrical portion.

The removable bushing 8 has an exteriorly screw-threaded portion 9 for engagement with the screw-threaded outer end 4 of the bore of the shell and the said bushing also has a flaring bore 10 (in the present instance an outwardly flaring bore) terminating at its smaller end in an annular shoulder 11.

The shank 12 of the center spindle has a screw-threaded outer end 13 for the reception of the terminal nut 14. A head 15 is provided at the inner end of the shank 12 formmg an annular shoulderv 16 facingthe inner end of the bushing 8. This head is of.

spherical form, substantially following and spaced from the spherical portion 5 of the shell bore. This head 15013 the center spindle has an axial hole 17 into whiclris driven the center electrode 18. The means which I employ for locking the electrode in the said hole comprises a hard metal ball 19 located in a slightly outwardly flaring axial hole 20 in the outer end of the electrode, so that as the electrode is fogced into the 30, 1925. Serial No. 5,756.

hole 17 in the head, the ball will crowd the walls of the hole 20 in the electrode tightly againstthe walls of the hole 17.

The shell 1 is provided with an inclined electrode 21 projecting into the proper spaced relationship to the center electrode 18 in the restricted passage 3, formed by the reduced inner end of the shell bore. The inclination of the electrode 21 with respect to the electrode 18 permits a greater sparking area at the inner end of the electrode 21.

A tube 22 of suitable insulating material,

such as wrapped mica surrounds the shank -12 of the spindle and extends from the shoulder 16 at the head to the screwthreaded outer end of the spindle shank.

A mass of insulating material, such as a plurality of superposed mica washers 23 surrounds the insulating tube 22 and is 1011- gitudinally compressed between the inner end of the bushing 8 and the shoulder 16 of the head, the exterior of Which mass is flared outwardly'from the head to the bush- 1ng, to gradually constrict' the space between the mass' 23 and the cylindrical portion 6 of the shell bore. This mass 23 may, if desired, be provided with external transverse corrugations to present a greater exposed surface.

Another mass of insulating material 24 surrounds the insulating tube 22 between the bushing 8 and the terminal nut 14, a washer 25 of asbestos, for instance, being inserted between the mass and the outer end of the bushing and a resilient cap 26 of brass, for instance, and a washer 27 of asbestos, for instance, being inserted between the outer end of the mass and the terminal nut.

The means which I employ for ensuring a gas tight joint between the bushing and spindle is as follows "A sleeve 28 of soft or malleable material, as brass, for instance, surrounds the insulating tube 22 within the outwardly flaring bore v10 of the bushing, A tubular wedge 29 of metal such, for instance, as soft steel, surrounds the sleeve 28, the inner and outer 'walls of said tubular wedge fitting the sleeve to form a gas tight joint around the spindle. The shoulder 11 at the smaller inner end of the flaring bore in the bushing serves to limit the inward movement of the sleeve as the tubular wedge is forced inwardly, to compress the sleeve.

A gasket 30 is clamped between the inner end of the bushing and the annular shoulder 7 in the shell bore to form a gas tight joint between the bushing and shell.

From the above description it will be seen that I have provided a very simple and effective device for locking the center electrode to its spindle. It will also be seen that I have provided asimple and eflective device for locking the spindle to the bushing with a gas tight joint, the use of the sleeve of compressible material between the tubular wedge and insulating tube efi'ectually protecting the tube from damage when the wedge is forced inwardly to compress the sleeve around the tube.

It is evident that Various changes may be resorted to in the construction, form and arrangement of the several parts without incense departing from the spirit and scope of my invention; hence, I do not intend to be limited to the particular embodiment here in shown and described, but

lrVhat I claim is:--

1. In a spark plug, a center spindle having a hole in its inner end, an electrode fitting said hole and itself having a hole in its outer end, and a separate piece located in said holes, acting as a wedge to crowd the walls of the electrode hole laterally into locking'engagement with the Walls of the spindle hole.

2. In a spark plug, a center spindle having a hole in its inner end, an elect-rode fitting said hole and itself having a hole in its outer ends, and hard. metal ball located in said holes, arranged to crowd the walls of the electrode hole laterally into locking engagement with the walls of the spindle hole.

In testimony, that I claim the foregoing as my invention, I have signed my name this 28th day of January 1925.

ARTHUR R. MOSLER. 

